We begin with a reversal of fournl for a famous defendant in a famous trial, a trial that riveted this nation a decade ago, michael skakel, known as a nephew in the kennedy family was convicted of murdering a young girl, and here he was, the person we saw then, skakel being led off to prison. But here he is today walking outside, free on bail and awaiting a new trial. So what was the big new twist in the case that has fascinated crime watchers for so long? Abc's ron claiborne starts us off. Reporter: Tonight, michael skakel is a free man, still insisting he was wrongly convicted of a crime he did not commit. Hopefully, we are at the first step of righting that wrong. Reporter: The case combines money, power, and one of america's most famous families. Skakel is the nephew of robert f. Kennedy and his wife, ethel. His arrest for the 1975 brutal murder of his pretty, young neighbor had the public transfixed from the very beginning. It happened in ritzy greenwich, connecticut. 15-year-old martha moxley was found under a tree in her family's back yard, bludgeoned to death with this golf club. There were no witnesses to the crime, no dna evidence. Skakel was also 15 at the time of the murder. But he wasn't charged until 25 years later, largely on the testimony of a prep school pal who said skakel confessed, saying, "i'm going to get away with murder. I'm a kennedy." A man named michael skakel witness stand convicted of murdering a teenager -- Reporter: A tiny prison cell like this has been skakel home for the last decade. He passed the years painting, a lobster, a clown -- this one titled, "faith." All the while, the kennedy family used their millions and their might to win his freedom. It was an attractive narrative for people that somehow this kid, because of his connections to my family which were very tenuous by the way, had gotten away with murder. The fact is that he didn't commit the murder. Reporter: Just a few weeks ago an appeals judge threw out skakel's conviction saying his former lawyer had bungled his defense and was released on $1.2 million bond. Outside the court martha moxley's mother put on a brave face. I'm disappointed but this is life. Reporter: Skakel could still be retried but that could take months, even years, if it happens. Tonight, diane, skakel is home, visiting with family. As we said, a big reversal. Thank you so much, ron claiborne.

This transcript has been automatically generated and may not be 100% accurate.

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